1. Field of the Invention
The present invention relates to a vaporizer for adding moisture to the atmosphere in a room, and more particularly, to a vaporizer with control circuitry that allows for faster warm-up and that regulates the output of steam, regardless of the conductivity of the water in the vaporizer.
2. Discussion of Prior Art
Vaporizers are devices for generating steam, and serve as humidifiers by releasing steam into the atmosphere of a room, thereby adding moisture to the air. A common type of steam vaporizer is an electric vaporizer, which includes a pair of parallel electrodes, spaced apart and extended into water held in a reservoir. Electric current passes between the electrodes to heat the water sufficiently so that it creates steam. Typically, the electrodes are contained within a boiling chamber having a relatively small volume, such that the electrodes only need to heat the water within the boiling chamber, rather than the water in the entire reservoir. Examples of such prior art vaporizers are disclosed in U.S. Pat. Nos. 4,132,883, 4,288,684 and 4,155,001, all of which are expressly incorporated herein by reference.
Prior art vaporizers suffer from a number of shortcomings. Prior art vaporizers do not adjust to the conductivity of the water used in the vaporizer. This leads to variability in the amount of steam generated, depending on the type of water used. For example, the conductivity of different sources of water, such as tap water, can vary greatly. If the water is hard (i.e. contains a large amount of dissolved minerals), then the conductivity of the water will be high relative to water which is soft (i.e. contains a relatively small amount of dissolved minerals). Water of higher conductivity will boil too quickly, generating too much steam and ejecting hot water, whereas water of lower conductivity will generate too little steam.
Prior art vaporizers also do not take into account changes in the conductivity of the water during operation. The conductivity of water increases as it heats. Therefore the power level of the electrodes in prior art vaporizers starts low and only reaches the proper level after the water starts to boil. This leads to longer warm-up times.
Attempts have been made to correct for these faults. U.S. Pat. No. 4,155,001 (Schossow) discloses a device that attempts to control the amount of steam released through the use of an adjustable valve. However, this method is not very effective because the rate of production of steam is not actually controlled. Instead, the adjustable valve simply controls the size of the aperture that releases steam from the vaporizer. This arrangement only provides for coarse adjustment of steam release. Moreover, the Schossow reference does not teach a way of regulating the current of the electrodes, so that warm-up times are reduced and the rate of steam generated is maintained at a relatively constant rate despite changes in the conductivity of the water.
Accordingly, what is needed is a vaporizer that adjusts to the conductivity of the water in the vaporizer to decrease warm-up time and maintain a more constant boiling rate and constant discharge of steam.
The present invention is a vaporizer that adjusts to the conductivity of the water used in the vaporizer, and also adjusts to changes in the conductivity of the water while in operation, thereby decreasing warm-up time and maintaining a relatively constant boiling rate and rate of steam production. More particularly, the present invention is directed to a vaporizer with a hardware circuit or other logic means designed to maintain a relatively constant boiling rate and production of steam. The present invention includes a control circuit or other logic means that adjusts the current supplied to a pair of electrodes in a vaporizer in response to the conductivity of the water, thereby controlling the boiling rate of the water and, hence, the production of steam. The present invention also includes a method of maintaining a relatively constant boiling rate by adding a fixed amount of salt to water in a vaporizer to raise the conductivity of the water to a minimum level, using a circuit or other logic means to maintain the power supplied to the electrodes of the vaporizer at a relatively high level to increase warm-up time, and adjusting the current supplied to the electrodes while the vaporizer is in operation and after the warm-up time to maintain a relatively constant rate of steam production.